Electromagnetic fluid pumps of the type taught by Wertheimer in U.S. Pat. No. 3,400,663 or by Brown in U.S. Pat. No. 4,079,436 have found wide acceptance for a variety of uses in both the industrial and commercial markets. One of the problems encountered in the use of these pumps is that they have a tendency to drain and loose their prime when they are located above the fluid reservoir or to siphon fluid from the fluid reservoir when they are located below the level of the fluid reservoir. This problem has been addressed by the prior art in a variety of ways. Barthalon in U.S. Pat. No. 4,021,151 discloses a reciprocating piston air pump in which the outlet ports are disposed in the side walls of the compression chamber. In the unactuated state of the pump the piston is biased to a full upward position in which the side walls of the piston block the outlet passages. Toyoda in U.S. Pat. No. 4,252,505 discloses a reciprocating piston fluid pump having a separate spring biased valve member to block the pump's outlet port when the pump is de-energized. The separate valve member is displaced to the open position by a separate solenoid coil. Nakamura in U.S. Pat. No. 3,877,841 and Nomura in U.S. Pat. No. 4,255,094, like Toyoda, disclose a separately movable valve member to block or shut off the pump's outlet port when the pump is de-energized. This movable valve is open only when the solenoid coil is energized. The present invention is a solution to the siphoning and draining problems which eliminates the need for a separate movable valve to close the outlet port when the solenoid coil is de- energized.